Producing cars and getting the public to buy them is a demanding and highly competitive business. Manufacturers agonize over ways to make their cars, trucks and SUVs even marginally better than another company's vehicles.
To make sure cars live up to the consumers' standards and one-up competitors, car makers test their cars in all types of environments. While much testing can be done on closed tracks, real-world car testing needs to take place in real-world conditions. By combining data from the track with information gleaned from driving on public roads, automakers use testing to create vehicles that they hope will satisfy the market.
This broad process covers everything from performance and comfort to reliability and safety. It also encompasses quality and appearance. The idea behind car testing is that it allows manufacturers to work out all the kinks and potential problems of a model before it goes into full production. It's much cheaper to eliminate a problem with a product before you begin mass producing it than it is to discover problems and try to fix them afterward.
One of the more well-known tests is crash testing. Slow-motion films are produced for cars being crash tested with dummies inside “playing” car passengers. Depending on the purpose of the film, the mannequin either goes flying through the windshield, or is protected by a car seatbelt and airbag. Manufacturers like to sound the proverbial trumpet when one of their vehicles, especially a family-oriented vehicle, scores well in government and independent crash-safety tests.
Depending on what's being measured or tested, engineers can make changes on the spot. In other cases, test findings may require an extensive rethinking of how a part or set of parts function. To make sure the entire testing process stays reasonably on schedule, manufacturers make multiple “test mules,” or pre-production cars, for testing. This way, multiple systems can be designed and experimented with at once.
Testing automobiles is expensive. The automobile prototypes, or test mules, can cost several hundred thousand dollars, even for so-called economy cars. Furthermore, it requires paying the salaries of teams of engineers, paying for the costs of special measuring equipment, and shelling out for meals and accommodations for these small armies when they must conduct their experiments away from their main offices.
In order to save costs for car manufacture, one of methods to reduce the number of crash tests is to computer simulated crash tests. With advance of the computers, a computer related technology called Computer aided engineering (CAE) has been used for supporting engineers in many tasks. For example, in a product design procedure, CAE analysis particularly finite element analysis (FEA) has often been employed to obtain and evaluate simulated structural responses (e.g., stresses, displacements, etc.) under various loading conditions (e.g., static or dynamic).
FEA is a computerized method widely used in industry to simulate (i.e., model and solve) engineering problems relating to complex products or systems (e.g., cars, airplanes, etc.) such as three-dimensional non-linear structural design and analysis. FEA derives its name from the manner in which the geometry of the object (e.g., an automobile) under consideration is specified. The geometry is defined by finite elements (or elements) and nodes. There are many types of elements, solid elements for volumes or continua, shell or plate elements for surfaces and beam or truss elements for one-dimensional structural objects. One of the most challenging tasks is related to numerically simulate an impact event between objects, for example, numerical simulations of automobile crashworthiness.
Car including components can be modified for improvement based on numerically calculated structural behaviors obtained in a numerical simulation. For example, any new physical change or modification in a car design can be numerically verified.
In a time-marching simulation (i.e., a particular kind of numerical simulation) of automobile crashworthiness (e.g., an automobile crashing into a fixed barrier), contacts between an automobile (represented by a FEA model) and a barrier, and self contacts amongst the finite elements of the FEA model must be detected and treated to realistically represent the physical phenomena. As modern computer technology progresses, the average FEA model used in automotive crashworthiness has become larger than ever (e.g., more than five million finite elements). It is becoming common to model cast aluminum parts with highly refined meshes of solid elements, rather than shell or beam elements used in the recent past. Modeling with solid elements allows sophisticated three-dimensional constitutive failure models; consequently, during a simulated crash event, the cast aluminum parts represented with solid elements can fragment creating disjoint debris which interacts in the contact treatment. A single piece of disjoint debris can be represented with one or more finite elements. Once a disjoint debris moves away from the main structure (i.e., the FEA model of the car), it no longer influences the simulation results, but can increase runtime dramatically as the search domain for contacts continuously grows in volume. During the simulation the search domain is modified in global space and is resized to contain the FEA model in its instantaneous state. If the search domain significantly grows, needed computer resources (e.g., computer processing time) required for detecting contacts and tracking finite elements that have broken free from the main structure can become disproportionally large compared to other tasks in the simulation. In certain circumstances, increased computing time can make a simulation impractical (each simulation generally needs to be done with an overnight execution). The need for efficient contact management is readily apparent.
It would therefore be desirable to have methods and systems for efficient contact management in numerical simulation of structural behaviors in an impact event between two objects.